Regenerative heat exchanger



Oct. 28, A. T, BOWDEN ETAL REGENERATIVE HEAT EXCHANGER Filed March a,1949 Patented Oct. 28, i952 'fors ottone-fthidto C. A. vParsonsvdtCompanyy Limited, Newcastleupon-,-Tyne, England.l

Application March 8, 1949;.Serial N. '$0,245

In creat Britain December 12; 1941- f- 5 Claims. (Cl. 25,719.61; l. 1

This invention relates to combustion turbines of all types embracingthose in which the working fluid may be obtained from a solid, liquid,or gaseous source, for instance, gas, oil, or coal, and which may beproduced either internally or externally.

This invention relates more particularly to heat exchangers of theregenerative drum type, in which the rotor, consisting of a cylindricalmatrix of metal or ceramic, rotates within a casing through which boththe exhaust gases and the compressed cold air pass. The paths of theexhaust gases and of the compressed air respectively are separated bysealings running along the length and around the ends of the drum,thereby dividing the drum into a hot gas and cold air side respectively,in which the gas can flow in counter directions through the matrix. Thehot exhaust gases, in passing through the hot gas side of the drum, giveup their heat to the matrix in that part of the drum, so that as thedrum rotates, the hot matrix passes into the cold air side, where theheat is transferred from the matrix to the cold compressed air. e

With this type of regenerator, the length of the gas or air path throughthe matrix, can be very small, but the temperature difference between,say, the inside diameter and outside diameter of the drum, is the fulltemperature difference between the hot gas and cold air temperatures, sothat the various parts of the drum are subjected to vary largedifferences of temperature. In order to maintain an effective seal alongthe length of the drum, it is important to keep the drum as nearlycylindrical in shape a-s possible.

The object of the present invention is to provide a drum overcoming orminimising the tendency to distortion, caused by the stresses set up bythe temperature differences in the metal of the drum.

Referring to the accompanying diagrammatic drawings, illustrating oneform of the present invention:

Figure 1 is a transverse section of a split drum, and

Figure 2 is a section on the line 2-2 of Figure 1 looking in thedirection of the arrows.

In carrying the invention into eiiect in the form illustrated, a drum issplit into foursections c along its length, the sections being heldtogether by bolting or similar means between two end plates a and b.Each section c of the drum consists of a number of separate chambers dkformed by a series of radial ribs e which connect the inside and outsidewalls of the drum con- 2 e centrically. The separate sections c of thefull drum are joined together in such a manner that the ribs e are allin line so that the chamber d runs the full length of the drum. Intothis chamber a'matrix of metal gauze or ceramic is fitted in such amanner that air or gas can flow from the inside to the outside of thedrum, or vice versa. The inside wall w and outside wall w of the drumare pierced with holes or slots f and g, through which the gas or aircan flow.

If it be assumed that in one half of the drum the cold air flows fromthe inside to the outside,

while in the other half of the drum the hot gas flows from the outsideto the inside, then the outside wall w of the drum will be at a suitablyhigher temperature than the `inside wall'w. Thus there is a tendency forthe outside wall to expand relative to the inside wall in thecircumferential direction. This expansion of the outside wall relativeto the inside wall is allowed for by having slots h in the ribs e in alongitudinal direction. Since the outside wall of the drum isconstrained by the ribs e, any excessive expansion of the outside wallwill tend to close up `the gap of the slits h.

In carrying this invention into effect in one way, it has been desired,from the -point of View of simplicity in manufacture, to build up thedrum in a longitudinal direction by the combining of a number of similarsections c. With this arrangement, it is necessary to secure the drumsections between the end plates a and b. The sections are, therefore,secured by a series of longitudinal bolts joining the end plates andpassing through the coldest wall-in the case under consideration, theinside wall--of the drum. since the bolts should be subjected to theleast distortion induced by any temperature changes to which the drummay be subjected.

In operation, the outside wall will tend to expand in a longitudinaldirection relative to the inside wall, and in order that no or littledistortion of the end plates a and b should occur, the sections c of thedrum are manufactured in such a way as to leave a gap i which becomesclosed as the temperature of the outside wall of the drum reaches theoperating temperature of the unit.

We claim;

1. vA rotor for a drum-type regenerative heat exchanger comprisingconcentric inner and outer walls and a plurality of radial ribs spaceduniformly around the circumference, connecting the inner and outer wallsand dividing the space between the inner and outer walls into aplurality 3 of chambers for holding a heat exchanging matrix.

2. A rotor according to claim 1, in which the inner and outer walls haveholes through which gas and air can flow.

3. A rotor according to claim 2, in which the ribs are gas tight.

4. A rotor according to claim 2, in which the rotor comprises an alignedplurality of annular sections fastened together with the inner wallsabutting and in which their outer walls are spaced apart providing axialclearance to accommodate for expansion when the sections are heated.

5. A rotor according to claim 2, in which the outer wall has radialslits continuing part way through the ribs toward the inner wall forpermitting expansion of the rotor wall between the ribs.

ANDREW THOMSON BOWDEN. PAUL KOLB.

REFERENCES CITED The following references are of record in the file ofthis patent:

y y UNITED STATES PATENTS Number Name Date 1,516,108 Ljungstrom et a1.Nov. 18, 1924 1,843,252 Tcensfeldt Feb. 2, 1932 2,224,787 Horney Dec.10, 1940 FOREIGN PATENTS Number Country Date 543,093 Great Britain Feb.10, 1942 620,602 Great Britain Mar. 28, 1949

